JP6638077B2 - Head-up display device and video display device therefor - Google Patents

Description

  The present invention relates to a technology of a head up display (hereinafter, referred to as “HUD”) device, and particularly to a windshield (windshield) of a vehicle or a transparent or translucent plate provided immediately before the windshield. The present invention relates to a technology that is effective when applied to a HUD device that projects an image on a combiner that is a display member.

  In a vehicle such as an automobile, information such as a vehicle speed and an engine speed is usually displayed on an instrument panel (instrument panel) in a dashboard. Further, a screen such as a car navigation system is incorporated in a dashboard or displayed on a display installed on the dashboard. When the driver visually recognizes such information, it is necessary to move his line of sight greatly.As a technology for reducing the amount of line of sight movement, information such as vehicle speed and information such as instructions related to car navigation are provided by windshield. 2. Description of the Related Art A HUD device for projecting and displaying an image on a windshield or a combiner is known.

  As a technique related to the HUD, for example, Japanese Patent Application Laid-Open No. 2015-194707 (Patent Document 1) includes a device that displays an image, and a projection optical system that projects the image displayed on the display device. In addition, a display device that reduces the screen distortion over the entire viewpoint area of the observer and realizes miniaturization is described. In this conventional technique, the projection optical system has a first mirror and a second mirror in the order from the display device to the optical path of the observer. The angle of incidence of the first mirror in the major axis direction of the image, the angle of incidence of the first mirror in the minor axis direction of the image, the distance between the image display surface of the display device and the first mirror, and are visually recognized by the observer. It is described that the size of the HUD device can be reduced by configuring the relationship with the horizontal width of the virtual image to satisfy a predetermined relationship.

JP 2015-194707 A

  In a conventional HUD device, generally, as a light ray for displaying a virtual image, for example, linearly polarized light such as an S-polarized wave with respect to a reflection surface is often used in consideration of characteristics such as reflection. I have.

  On the other hand, a driver of a vehicle often uses sunglasses having a polarizing effect in order to selectively reduce glare on the road surface. However, in a conventional HUD device that displays a virtual image by using such linearly polarized light when sunglasses having a polarizing action are worn, there is a problem that the HUD image cannot be seen, as will be described later in detail.

  Therefore, according to the present invention, it is possible to view the HUD image even when wearing sunglasses having a polarizing action, and furthermore, as compared with the above-described conventional technology, it is modularized, small, and has high light use efficiency. An object of the present invention is to provide a HUD device and a video display device therefor.

  According to one embodiment of the present invention, there is provided a head-up display device for a vehicle, wherein an image is projected on the windshield or the combiner by polarized light. A head-up display device provided with means for converting the polarization of the polarized light of the image projected from the image display device on a part of the optical path from the image display device to the windshield or the combiner. You.

  Further, according to the present invention, there is provided an image display device for a head-up display device for a vehicle, comprising: a light source; a collimating optical system configured to convert light emitted from the light source into substantially parallel light; An image display device, comprising: a light guide that receives light emitted from the system and emits the light in a direction different from the incident direction, and further includes a polarization conversion element that aligns the polarization direction of the light in one direction. Is provided.

  According to the present invention described above, it is possible to solve the above-described problems in the related art, and realize a small-sized, high-efficiency modularized HUD device which can be manufactured at low cost, and a video display device therefor.

1 is a diagram illustrating an example of a basic configuration of a HUD device according to the present invention and an internal configuration of a video display device thereof. FIG. 4 is a diagram for explaining the principle of solving the problem in the related art in the present invention. FIG. 2 is an exploded perspective view showing an overview of the light source device of the video display device according to the first embodiment of the present invention. FIG. 1 is a perspective view illustrating an optical system overview of a light source device of a video display device according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating details of a collimator in the video display device according to the first embodiment. FIG. 2 is a perspective view illustrating an arrangement structure of a collimator and a polarization conversion element in the image display device according to the first embodiment. FIG. 3 is a perspective view showing a combined diffusion block arranged on an emission surface of a polarization conversion element in the image display device according to the first embodiment. FIG. 3 is a perspective view, a cross-sectional view, and a partially enlarged cross-sectional view illustrating details of a light guide in the image display device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view illustrating details of a reflection surface, a connection surface, and light ray reflection that constitute a light guide in the image display device according to the first embodiment. FIG. 3 is a top view and a side cross-sectional view illustrating a configuration and a state of light rays in the image display device according to the first embodiment. FIG. 6 is a diagram illustrating a comparative example for explaining the function of the light guide in the image display device according to the first embodiment. FIG. 4 is a diagram illustrating a method of processing a mold used to mold the light guide of the image display device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view showing an example of setting of a reflection surface, a connection surface, and light ray reflection forming a light guide in the image display device according to the first embodiment. FIG. 9 is a top view and a side cross-sectional view illustrating a configuration and a state of light rays in an image display device according to another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Basic configuration of HUD and principle of the present invention>
FIG. 1A shows a basic configuration of a HUD device according to the present invention. As is clear from this figure, the HUD device 100 basically includes a video display device 300 including a light source device composed of a projector, an LCD (Liquid Crystal Display), and the like, and light from the video display device (this In this case, the image light is reflected by a mirror 151 (for example, a free-form surface mirror or a mirror having an asymmetric optical axis) or another mirror 152, and the windshield 103 of the vehicle 102 or a combiner disposed immediately before the windshield 103 Project on 200. On the other hand, the driver 105 sees the image projected on the windshield 103 or the combiner 200, and visually recognizes the image as a virtual image ahead of the windshield 103 through the transparent windshield 103. At this time, the mirror 151 may be replaced with a concave mirror, and the other mirror 152 may be replaced with a cold mirror. Here, an example in which video light is projected onto the combiner 200 will be described to avoid redundant description.

  FIG. 1B shows an example of the internal configuration of the HUD device 100, in particular, the video display device 300 thereof. As is clear from this figure, a case where the image display device 300 constitutes a projector is shown, and the image display device 300 includes, for example, each unit such as a light source 301, an illumination optical system 302, and a display element 303. Have. In addition, by employing the light source device of the present invention described in detail below as the light source 301, it is possible to generate good illumination light for projection.

  In this example, the illumination optical system 302 is an optical system that collects illumination light generated by the light source 301 and irradiates the illumination light to the display element 303 in a more uniform manner, and the display element 303 is an element that generates an image to be projected. And is included. However, in the embodiment described below, these components are already used as the combined diffusion block 16, the first diffusion plate 18a, the light guide 17, and the second diffusion plate 18b as shown in FIG. Further, the liquid crystal display panel 52 is included in the light source device of the present invention (see the light source device case 11 in FIG. 3). Therefore, the light source device 10 (see FIG. 3) of the present invention can be used as it is as the video display device 300 of the HDU device 100. According to this, in particular, it is possible to realize the HUD device 100 that can be easily attached to a narrow space such as a dashboard in an automobile. It should be noted that the light emitted from the image display device 300 is further projected on the windshield 103 or the combiner 200 of the vehicle 102 via the display distance adjustment mechanism 400 and the mirror driving unit 500, if it is known to those skilled in the art. It will be obvious.

  Subsequently, referring to FIG. 2, in the present invention, when the driver wears the above-described problem, that is, sunglasses having a polarizing action (hereinafter, also referred to as “polarized sunglasses”), the linearly polarized light from the HUD device 100 causes The principle of eliminating the problem that the virtual image displayed on the windshield 103 or the combiner 200 of the vehicle 102 becomes invisible will be described. This figure shows an example in which the image light from the HUD device 100 is displayed on the combiner 200 instead of the windshield 103. However, the image light from the HUD device 100 is projected on the windshield 103. It will be obvious to those skilled in the art that the same is true in the case of doing so.

  The combiner 200 is formed, for example, by forming a polymer film 220 on the surface (the surface facing the driver side, the right side in the figure) of a substrate 210 made of a transparent plate member such as a polycarbonate plate or a glass plate. It is. The polymer film 220 is a film in which birefringent ellipsoids formed of a polymer are arranged in a predetermined direction, as indicated by a broken line ellipse in the figure. Reference numeral 230 in the figure denotes a half mirror attached to the back surface of the substrate 210, and reference numeral 240 denotes an antireflection (AR) formed on the surface of the polymer film 220, that is, on the outermost surface side of the combiner 200. ) Films are shown.

  When S-polarized image light from the HUD device 100 is incident on the combiner 200 as shown by a solid arrow in the drawing, the polymer film 220 is duplicated in a cross section normal to the incident light. The relationship between the principal axis of the refraction ellipsoid and the plane of polarization is shown at the lower left of the figure. That is, the polymer film 220 is attached so that the direction of the principal axis of the birefringent ellipsoid, which is the optical principal axis thereof, matches the polarization plane of the light incident on the combiner 200.

  According to such a configuration, light incident on the combiner 200 propagates along the main axis of the polymer film 220 as linearly polarized light. As a result, since the light is incident on the surface of the half mirror 230 with S-polarized linearly polarized light, it is possible for the half mirror to reflect the light rays constituting the HUD image with high reflectance.

  After that, the light beam is reflected by the half mirror 230 on the back surface of the substrate 210 and again enters the polymer film 220. On the other hand, with respect to the reflected light from the combiner 200, the relationship between the main axis and the polarization plane of the polymer film 220 in the normal line cross section of the reflected light is As shown in the lower right of the figure, the angles are different from each other. From this, the linearly polarized light reflected by the half mirror 230 is affected by the retardation of the polymer film as it propagates through the polymer film 220, and becomes elliptically polarized light.

  That is, the S-polarized image light from the HUD device 100 enters the driver's eyes as elliptically polarized light due to the action of the polymer film 220 constituting the combiner 200. General polarized sunglasses have a characteristic of blocking S-polarized light from the road surface and the windshield in order to block glare on the road surface and reflected light from the windshield. Therefore, in the conventional general HUD optical system, the HUD image cannot be recognized by wearing the polarized sunglasses. However, in the present invention, the light of the HUD image reflected by the windshield or the combiner is converted into elliptically polarized light. Since the HUD image is converted, it is possible to recognize the HUD image even when wearing polarized sunglasses.

  In the above example, as one means for converting S-polarized image light into elliptically polarized light, a polymer film 220 in which birefringent ellipsoids formed of polymers are arranged in a predetermined direction will be described. However, the present invention is not limited to this, and other means having the same effects as described above can be used. In the above description, the position of the polarization conversion means is such that the polymer film 220 is formed on the surface of the substrate 210 of the combiner 200 (the surface facing the driver side). However, the present invention is not limited to this, and although the reflectance at the windshield and the combiner is slightly reduced, such a polarization conversion unit is more suitable for an optical path through which the polarized image light from the image display device 300 propagates. Specifically, it can be arranged in a part of the optical path from the image light emission surface of the liquid crystal display panel 52 to the inner surface of the combiner 200 (or the windshield 103).

  The method for producing the polymer film is such that a relatively large photoelastic film such as polycarbonate is sandwiched between highly heat-resistant, for example, a metal plate or the like, and a shear stress is applied thereto while heating to t ° C. Is done. The above-mentioned t ° C. is preferably equal to or higher than the thermal softening point temperature of the polymer film, and is preferably lower than the melting temperature. Here, the polymer film was made of polycarbonate, and the heating temperature was 127 ° C. The method for producing the polymer film is not limited to the above, and can be appropriately selected depending on the material and the characteristics.

  Further, in the HUD device, it is necessary to consider damage to the HUD device due to sunlight itself. When the sun is present in a specific direction (in FIG. 2, the direction of θ with respect to the reflection surface of the combiner 200) as shown by a thick broken line ray 401 in FIG. 2, the ray is HUD as shown by a ray 401 p. Since the light travels backward in the optical path of the image light and reaches the image display device 300, the image display device may be damaged.

  In the present invention, in order to avoid the above-described damage, the reflectance of the S-polarized light of the half mirror 230 is set to 50% or more with respect to the light that enters the combiner from the outside at the incident angle θ as described above. I made it. By adopting this configuration, 50% or more of the S-polarized light of the sunlight with respect to the combiner surface is reflected to the outside as shown by a light ray 401s, and the remainder becomes a light ray 401p, and goes backward in the optical path of the HUD image light. The S-polarized light component and the P-polarized light component of the light beam 401 s are parallel or orthogonal to the principal axis of the birefringent ellipsoid of the polymer film as in the case of the HUD image light, so that the polarization state is preserved and propagated. Thereafter, the light is reflected by the mirror 151 shown in FIG. 1 and further reflected by the other mirror 152, and then enters the image display device 300. Here, the other mirror 152 has a so-called cold mirror configuration in which the reflectance is high with respect to visible light and low with respect to infrared light. The structure has a polarization characteristic in which the reflectance is as high as 90% or more and the reflectance for P-polarized light is 30% or less. According to this configuration, most of the P-polarized light component of the light beam 401p passes through the other mirror 152 as shown in the drawing, and does not reach the video display device 300. In order to provide the above-mentioned polarization characteristics, the incident angle の of the principal ray with respect to the other mirrors 152 is desirably 30 degrees or more. If the angle of incidence of the chief ray is smaller than 30 degrees, it is difficult to exhibit a sufficient change in reflectance characteristics depending on the polarization direction. By employing this configuration, most of the P-polarized light component is cut off from the combiner surface, and the remaining S-polarized light component is mainly used. Therefore, the sunlight reaching the image display device 300 is 30% or less of the P-polarized component and 50% or less of the S-polarized component, that is, 40% or less on average, with respect to the sunlight in the visible light region incident on the combiner 200. . Further, most of the infrared light is cut off by the other mirror 152, and the damage of the sunlight to the image display device 300 can be greatly reduced.

  On the other hand, since the HUD image light is emitted as S-polarized light from the display element 303 to the combiner 200, 90% or more of visible light is reflected by the other mirror 152, and the image light of the other mirror 152 is reflected. The effect on is small. Although not shown, instead of providing the other mirror 152 with the above-described polarization characteristics, a polarizing filter that blocks P-polarized light with respect to the combiner 200 between the combiner 200 and the image display device 300. The same effect can be obtained by installing. Further, the half mirror 230 can realize the above characteristics by laminating a predetermined number of dielectric multilayer films. In the above description, protection measures against damage to the HUD device due to sunlight in the case of a combiner have been described. However, when video light is reflected by a windshield instead of a combiner, the outer surface of the windshield is It will be apparent to those skilled in the art that the same measures as described above may be implemented.

<Detailed structure of video display device>
Subsequently, the configuration of the image display device 300 that emits S-polarized image light in the HUD device 100 will be described below, in particular, in order to realize a small-sized HUD device with high light use efficiency that is suitable for modularization. Will be described in detail below.

  FIG. 3 is a developed perspective view showing an overview of the video display device 300 according to the embodiment of the present invention. As is clear from the figure, the image display device (main body) 300 is formed of, for example, plastic or the like, and houses therein an LED, a collimator, a combined diffusion block, a light guide, and the like, which will be described in detail later. The light source device case 11 of FIG. The liquid crystal display element 50 is mounted on the upper surface. On one side surface of the light source device case 11, an LED (Light Emitting Diode) element, which is a semiconductor light source, and an LED board 12 on which a control circuit thereof is mounted are mounted. A heat sink 13 for cooling the heat generated in the LED element and the control circuit is attached.

  Further, the liquid crystal display element 50 attached to the upper surface of the light source device case 11 includes a liquid crystal display panel frame 51, a liquid crystal display panel 52 attached to the frame, and an FPC (FPC) electrically connected to the panel. Flexible Printed Circuits 53). That is, the liquid crystal display panel 52 generates an image to be displayed according to a control signal from a control circuit (not shown here) constituting an electronic device together with an LED element which is a solid-state light source, which will be described in detail later. Controlled.

  Hereinafter, the configuration of the optical system housed in the image display device 300, that is, the optical system housed in the light source device case 11, will be described in detail with reference to the attached FIGS.

  In FIG. 4, a plurality of (two in this example) LEDs 14 a and 14 b (not shown here) constituting a light source are mounted at predetermined positions with respect to the LED collimator 15. Note that each of the LED collimators 15 is formed of a translucent resin such as polycarbonate, for example. As shown in FIG. 5, this LED collimator 15 has an outer peripheral surface 156 having a conical convex shape obtained by rotating a substantially parabolic cross section, and has a convex portion (that is, a convex portion at its top portion) at its central portion. (A convex lens surface) 157 is formed. In the center of the plane portion, a convex lens surface 154 protruding outward (or a concave lens surface concaved inward) 154 is provided. The parabolic surface (outer peripheral surface) 156 that forms the conical outer peripheral surface of the LED collimator 15 has an angle within a range in which light emitted from the LED 14a or 14b in the peripheral direction can be totally reflected inside. It is set or a reflection surface is formed.

  On the other hand, the LEDs 14a and 14b are respectively arranged at predetermined positions on the surface of the so-called LED board 12, which is the circuit board. As is clear from FIG. 5, the LED board 12 is arranged and fixed to the LED collimator 15 such that the LEDs 14a or 14b on the surface thereof are respectively located at the center of the concave portion 153. .

  According to such a configuration, of the light emitted from the LED 14a or 14b by the above-described LED collimator 15, particularly the light emitted upward (rightward in the drawing) from the central portion thereof is indicated by an arrow in the drawing. As shown, the two convex lens surfaces 157 and 154 forming the outer shape of the LED collimator 15 condense the light into parallel light, and the light emitted from other portions toward the peripheral direction is conical with the LED collimator 15. The light is reflected by the paraboloid (outer peripheral surface) 156 that forms the outer peripheral surface of the shape, and is similarly condensed into parallel light. In other words, according to the LED collimator 15 in which a convex lens is formed in the center and a paraboloid (outer surface) 156 is formed in the periphery, almost all of the light generated by the LED 14a or 14b is converted into parallel light. The light can be extracted, and the efficiency of using the generated light can be improved.

  Note that a polarization conversion element 21 described in detail below is provided on the light emitting side of the LED collimator 15. As shown in FIG. 6, the polarization conversion element 21 has a columnar transmissive member having a parallelogram cross section (hereinafter referred to as a parallelogram column) and a columnar section having a triangular cross section (hereinafter, referred to as a triangular column). And a plurality of light-transmissive members are arranged in parallel in a plane orthogonal to the optical axis of the parallel light from the LED collimator 15 and arranged in an array. Further, a polarizing beam splitter (hereinafter abbreviated as “PBS”) film 211 and a reflection film 212 are provided alternately at the interface between adjacent light-transmitting members arranged in an array. Further, a 1 / 2λ phase plate 213 is provided on an emission surface from which light that enters the polarization conversion element 21 and transmits through the PBS film 211 is emitted.

  The output surface of the polarization conversion element 21 is further provided with a rectangular composite diffusion block 16 also shown in FIG. That is, the light emitted from the LED 14a or 14b is converted into parallel light by the action of the LED collimator 15, enters the combined diffusion block 16, is diffused by the texture 161 on the emission side, and is then transmitted to the light guide 17 described below. Reach.

  Returning to FIG. 4, a light guide 17 having a substantially triangular cross section is provided on the emission surface side of the composite diffusion block 16 via a first diffusion plate 18a. Is provided with a second diffusion plate 18b. Thereby, the horizontal light of the LED collimator 15 is reflected upward in the drawing by the function of the light guide 17 and is guided to the incident surface of the liquid crystal display element 50. At this time, the intensity of incident light is made uniform by the first and second diffusion plates 18a and 18b.

  Details of the light guide 17 constituting the video display device 300 will be described below with reference to the drawings. 8A is a perspective view showing the entire light guide 17, FIG. 8B is a cross section thereof, and FIGS. 8C and 8D are details of the cross section. It is a partially expanded sectional view.

  The light guide 17 is, for example, a member formed in a rod shape having a substantially triangular cross section (see FIG. 8 (b)) by a translucent resin such as acrylic, and FIGS. 4 and 8 (a). As is clear, the light guide light incident portion (surface) 171 opposed to the emission surface of the composite diffusion block 16 via the first diffusion plate 18a, and the light guide light reflection portion (surface) forming the slope. 172) and a light guide light emitting portion (surface) 173 facing the liquid crystal display panel 52 of the liquid crystal display element 50 via the second diffusion plate 18b.

  As shown in FIGS. 8 (c) and (d), which are partially enlarged views, the light guide light reflecting portion (surface) 172 of the light guide 17 has a large number of reflection surfaces 172a and connecting surfaces 172b. Are alternately formed in a sawtooth shape. The reflection surface 172a (the line segment rising to the right in the drawing) forms αn (n: a natural number, for example, 1 to 130 in the present example) with respect to the horizontal plane indicated by the dashed line in the drawing. As an example, here, αn is set to 43 degrees or less (however, 0 degrees or more).

  On the other hand, the connecting surface 172b (in the figure, a line segment descending to the right) forms βn (n: a natural number, for example, 1 to 130 in this example) with respect to the reflecting surface. In other words, the connecting surface 172b of the reflecting portion is inclined at an angle which becomes a shadow within a range of the half value angle of the scatterer described later with respect to the incident light. .Alpha.1, .alpha.2, .alpha.3, .alpha.4... Form a reflection surface elevation angle, and .beta.1, .beta.2, .beta.3, .beta.4... Form a relative angle between the reflection surface and the connection surface. , 90 degrees or more (however, 180 degrees or less). In this example, β1 = β2 = β3 = β4 =... = Β122 =.

  9 and 10 are schematic diagrams in which the size of the reflection surface 172a and the connection surface 172b is relatively large with respect to the light guide 17 for explanation. At the light guide light incident portion (surface) 171 of the light guide 17, the main light beam is deflected by δ in a direction in which the incident angle with respect to the reflection surface 172a increases (see FIG. 10B). That is, the light guide light incident portion (surface) 171 is formed in a curved convex shape inclined toward the light source. According to this, the parallel light from the exit surface of the combined diffusion block 16 is diffused and incident via the first diffusion plate 18a, and as is apparent from the figure, the light guide light incident portion (surface). The light reaches the light guide light reflection portion (surface) 172 while slightly bending (deflecting) upward by 171 (see a comparative example in FIG. 11).

  In this light guide light reflecting portion (surface) 172, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape, and diffused light is totally reflected on each reflecting surface 172a. Then, the liquid crystal display panel 52 of the liquid crystal display element 50 is converted into parallel diffused light through the light guide light emitting portion (surface) 173 and the second diffusion plate 18b as shown in FIG. Incident on. Are set so that each of the reflection surfaces 172a is at an angle equal to or greater than the critical angle with respect to the diffused light, while the reflection surfaces 172a and the connection surfaces 172b are set. Are fixed angles as described above, and the reason is described later, but is more preferably set to an angle of 90 degrees or more (βn ≧ 90 degrees). .

  According to the above-described configuration, since each of the reflection surfaces 172a always has an angle equal to or greater than the critical angle with respect to the diffused light, a reflection film such as a metal is formed on the light guide light reflection portion (surface) 172. Even without formation, total reflection is possible, and a low-cost light source device can be realized. On the other hand, as shown in FIG. 11 which is a comparative example, when there is no bending (polarization) of the main light beam at the light guide entrance of the light guide 17, a part of the diffused light is reflected on the reflection surface 172a. , The critical angle is less than the critical angle, and a sufficient reflectivity cannot be ensured, so that a light source device with good characteristics (bright) cannot be realized.

  Further, the reflection surface elevation angles α1, α2, α3, α4,... Are values that gradually increase as the light guide light reflection portion (surface) 172 moves from the lower portion to the upper portion. This is because light transmitted through the liquid crystal display panel 52 of the liquid crystal display element 50 has a certain divergence angle, and in particular, a part of the light transmitted through the periphery of the liquid crystal display panel 52 is disposed downstream. For the purpose of preventing the so-called marginal dimming occurring at the periphery of the mirror, as shown by a ray 30 in FIG. 9, this is to realize a configuration in which the rays in the peripheral part are slightly deflected in the direction of the central axis.

  As described above, β1 = β2 = β3 = β4... Βn ≧ 90 degrees. This is because, as shown in FIG. 12, the mold 40 for manufacturing the light guide 17 by injection molding is used. This is because, in the processing, the reflecting surface 172a and the connecting surface 172b can be simultaneously processed by the end mill 35 in which the relative angle between the bottom surface and the side surface is β. In addition, since the reflection surface 172a and the connection surface 172b can be processed with a relatively thick tool, the processing time can be significantly reduced, and the processing cost can be significantly reduced. Further, the boundary edge between the reflection surface 172a and the connection surface 172b can be processed with high accuracy, and the light guide characteristics of the light guide 17 can be improved.

  In FIG. 9, Lr1, Lr2, Lr3, Lr4... Represent the projection length of the reflection surface 172a on the horizontal plane, and Lc1, Lc2, Lc3, Lc4. Lr / Lc, that is, the ratio between the reflection surface 172a and the connection surface 172b can be changed depending on the location. The intensity distribution of the main light beam 30 incident on the light guide 17 does not always coincide with the intensity distribution desired on the incident surface of the liquid crystal display panel 52. Therefore, a configuration in which the intensity distribution is adjusted by the ratio Lr / Lc between the reflection surface 172a and the connection surface 172b is adopted. It should be noted that the higher the ratio, the higher the average intensity of the reflected light at that portion. In general, the light beam 30 incident on the light guide tends to be strong at the central portion. Therefore, in order to correct this, the ratio Lr / Lc is configured differently depending on the location. I made it. Since the ratio Lr / Lc varies depending on the location and the above-described reflection surface elevation angles α1, α2, α3, α4... Vary depending on the location, the envelope representing the general shape of the light guide light reflecting portion (surface) 172. 172c shows a curved shape as shown in FIG.

  Further, Lr1 + Lc1 = Lr2 + Lc2 = Lr3 + Lc3 = Lr4 + Lc4... = Lr + Lc ≦ 0.6 mm. According to such a configuration, the repetition pitch of the reflection surface as viewed from the light guide light emitting portion (surface) 173 of the light guide 17 can be made the same. In addition, since the pitch is 0.6 mm or less, when viewed through the liquid crystal display panel 52, the individual emission surfaces are not separated and appear as continuous surfaces when viewed through the liquid crystal display panel 52, in combination with the operation and effect of the diffusion plates 18a and 18b. Accordingly, the spatial brightness over the liquid crystal display panel 52 can be made uniform, and the display characteristics can be improved. That is, according to this configuration, it is possible to make the incident light intensity distribution on the liquid crystal display panel 52 uniform. On the other hand, if the value of Lr + Lc is smaller than 0.2 mm, not only processing time is required but also it is difficult to precisely process each reflecting surface 172a.

  According to the shape of the light guide light reflecting portion (surface) 172 of the light guide 17, the condition for total reflection of main light can be satisfied, and the light guide light reflecting portion (surface) 172 is made of aluminum or the like. There is no need to provide a reflective film, light can be reflected efficiently, and there is no need to perform an operation of depositing an aluminum thin film, which requires an increase in manufacturing cost, and a brighter light source can be realized at lower cost. In addition, each relative angle β is set to an angle such that the principal ray 30 of the connecting surface 172b becomes a shadow with respect to the light diffused by the combined diffusion block 16 and the diffusion plate 18a. Thus, by suppressing the incidence of unnecessary light on the connecting surface 172b, the reflection of unnecessary light can be reduced, and a light source device with good characteristics can be realized.

  According to the light guide 17 described above, the length of the light guide light emitting portion (surface) 173 in the optical axis direction can be reduced by appropriately setting the reflection surface elevation angles α1, α2, α3, α4. Since the size (surface size) of the light guide light emitting portion (surface) 173 can be freely changed, the size (surface size) of the light guide light emitting portion (surface) 173 can be changed with respect to the device such as the liquid crystal display panel 52. It is possible to realize a light source device that can be appropriately changed to a required size (surface size), which is suitable for. This also enables the light guide light emitting portion (surface) 173 to have a desired size without depending on the arrangement shape of the LEDs 14a and 14b constituting the light source, and thus has a desired size. Thus, a planar light emitting source can be obtained. Furthermore, it leads to securing the degree of freedom in the design including the arrangement of the LEDs 14a and 14b constituting the light source, which is advantageous for miniaturization of the entire device.

  In addition, according to the above-described light guide 17, as shown in FIG. 13, the connecting surface 172b constituting the light guide light reflecting portion (surface) 172 is appropriately set (in this example, the central portion of the light guide portion 172) is formed. According to the configuration in which light is not reflected on some of the reflection surfaces 172a), the ratio Lr / Lc of the reflection surface 172a and the connection surface 172b in the light guide light emitting portion (surface) 173 of the light guide 17 is reduced. It can be changed depending on the location. In the example shown in the figure, the light display at the light guide light emitting portion (surface) 173 of the light guide 17 is divided into left and right in the direction of the optical axis. This case is particularly suitable for a case where the virtual image screen is displayed vertically and horizontally separated in the HUD device.

  Here, it is generally desirable that the inclination of the main light beam incident on the liquid crystal display panel 52 be close to vertical, however, depending on the characteristics of the liquid crystal display panel, as shown in FIG. It is also possible to incline by the angle η. That is, some commercially available liquid crystal display panels have better characteristics when the incident angle is tilted by about 5 to 15 degrees. In this case, the above η is set to 5 to 15 in accordance with the characteristics. Degree is desirable.

  Instead of tilting the liquid crystal display element 50 by η, it is also possible to tilt the tilt of the main light beam to the liquid crystal display panel 52 by adjusting the angle of the reflection surface 172a. Further, when it is necessary to incline the inclination of the light beam in the side direction of the light guide, the inclination of the triangular texture 161 formed on the exit surface of the synthetic diffusion block 16 is made asymmetrical or the reflection surface It can be realized by changing the forming direction of the texture composed of 172a and 172b.

  As described in detail above, according to the image display device 300 of the present invention, the light use efficiency of light from the light source and its uniform illumination characteristics are further improved, and at the same time, a compact light source device is used. In addition, it can be manufactured at low cost.

  That is, according to the above-described video display device 300, the light incident on the liquid crystal display panel 52 constituting the liquid crystal display element 50 is converted into the S-polarized wave by the polarization conversion element 21, so that the liquid crystal display panel The transmittance at 52 can be improved. Therefore, a smaller and more efficient modular light source device can be realized at a lower cost with a smaller number of light emitting sources (LEDs). In the above description, the polarization conversion element 21 is mounted after the LED collimator 15. However, the present invention is not limited to this, and the same effect can be obtained by providing the polarization conversion element 21 in the optical path to the liquid crystal display element. It will be apparent to those skilled in the art that the effect can be obtained.

<Other Examples>
As shown in FIG. 14, the light guide 17 disposed behind the synthetic diffusion block 16 may be constituted by a polarization conversion element (light guide 17 ′) instead of a normal translucent resin. It is. In addition, in this structure, as is clear from the figure, the light transmitting member 211 ′ of a triangular prism and the light transmitting member 212 ′ of a parallelogram column are combined, and the boundary surface thereof is formed by the LED 14 a or 14 b. The S-polarized wave (see the symbol (x) in the figure) of the incident light that has been emitted and turned into parallel light by the LED collimator 15 is reflected, while the P-polarized wave (see the upper and lower arrows in the figure) is reflected. A transparent PBS film 211 is formed, and a λλ phase plate 213 is formed on the upper surface of the light-transmissive member 212 ′ in the form of a row quadrilateral, and a reflective film 212 is formed on the side surface thereof. I have.

  According to the configuration described above, as is apparent from the figure, the incident light emitted from the LED 14 a or 14 b and converted into parallel light by the LED collimator 15 is converted into a light guide 17 composed of a polarization conversion element instead of the light guide 17. As a result, the light is polarized into an S-polarized wave and emitted upward from the upper surface of the element. That is, in the above-described configuration, the size of the device can be significantly reduced, and the manufacturing cost of the device can be reduced, particularly by removing the light guide 17 made of a normal translucent resin.

  The configuration of the video display device for realizing a small-sized HUD device with high light use efficiency suitable for modularization according to the embodiments of the present invention has been described above. However, the S-polarized image light from the image display device to the windshield or the combiner converts the image light reaching the driver's eyes into elliptically polarized light by the action of the polymer film 220 constituting the windshield or the combiner. As described above, it becomes possible to recognize the HUD image even when the polarized sunglasses are worn by the conversion.

  As described above, various embodiments have been described in detail. However, the present invention is not limited to the above-described embodiments, but includes various modifications. For example, in the above-described embodiment, the entire apparatus is described in detail in order to easily explain the present invention, and the present invention is not necessarily limited to the apparatus having all the configurations described above. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. Further, for a part of the configuration of each embodiment, it is possible to add, delete, or replace another configuration.

  100 HUD device, 300 image display device, 102 vehicle, 103 windshield, 200 combiner, 210 substrate, 220 polymer film, 230 half mirror, 50 liquid crystal display device, 10 light source device 11 light source device case, 12 LED board, 13 heat sink, 50 liquid crystal display element, 51 liquid crystal display panel frame, 52 liquid crystal display panel, 53 FPC (flexible wiring board), 14a, 14b, LED 15 LED collimator, 17 light guide, 18a, b diffusion plate, 172a reflection surface, 172b connection surface, 16 synthetic diffusion block, 161 texture, 21 polarization conversion element, 211 PBS film, 212 ... reflection film, 151 ... mirror, 152 ... other mirror.

Claims (8)

A head-up display device for a vehicle,
On a windshield or a combiner, an image display device that projects an image with polarized light,
A half mirror surface is formed on the windshield or the combiner. The half mirror reduces the reflectance of S-polarized light when sunlight enters the optical path of the image light of the head-up display device at a reverse angle. A head-up display device having 50% or more. The head-up display device according to claim 1 ,
A head-up display device, comprising an optical element between the windshield or the combiner and the video display device for selectively reducing a component of P-polarized light with respect to the windshield or the combiner. The head-up display device according to claim 2 ,
The head-up display device, wherein the optical element is a mirror having a reflectance of 90% or more for S-polarized light and a reflectance of 30% or less for P-polarized light. The head-up display device according to claim 3 ,
The head-up display device, wherein the optical element doubles as a cold mirror. The head-up display device according to claim 4 ,
A head-up display device, wherein an incident angle の of a principal ray emitted from the video display device with respect to a mirror constituting the optical element is 30 degrees or more. The head-up display device according to claim 2 ,
The head-up display device, wherein the optical element is a polarizing filter. A head-up display device for a vehicle,
An image display device that projects an image on a windshield or a combiner with polarized light, and a reflectance of S-polarized light of 90% or more and a reflectance of P-polarized light between the windshield or the combiner and the image display device. A head-up display device in which 30% or less of mirrors are arranged, and the mirrors also serve as cold mirrors. The head-up display device according to claim 7 ,
A head-up display device, wherein an angle の of a principal ray emitted from the video display device with respect to a mirror constituting an optical element is 30 degrees or more.

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